Continuous swimming tanks are known generally. German Patent No. 2,222,594 issued to Hoppe shows a continuous swimming tank. In the tank described therein, water circulates from the front of a swimming area past the swimmer to the rear of the swimming area where it is recirculated through a duct which runs beneath the floor of the swimming area. One set of turning vanes directs the water from the swimming area to the recirculation duct. The water passes over a propeller located in the duct and used for circulation. The second set of turning vanes directs the water from the recirculation duct back into the front of the swimming area.
The swimming area shown in the German '594 patent widens from the front of the tank to the rear of the tank. That is, the cross-sectional area of the swimming area increases from the front to the rear of the tank. This results in velocity variations over the length of the tank. The velocity of the flowing water is greater at the front of the swimming area than it is at the rear of the swimming area. Thus, a swimmer may choose where to swim, according to water velocity. The flow rate of water is constant anywhere in a given cross-section, perpendicular to the direction of water flow. The preceding prior art is incorporated by reference herein.
The problem with such a design is that it requires a large swimming area and thus a large swimming tank. Further, a large motor and great deal of power is required to circulate such a large volume of water.
U.S. Pat. No. 2,035,835 issued to Raber for “Swimming Bath” shows a continuous swimming tank. In this reference, water is circulated either beneath the floor of the swimming area or around the sides of the swimming area. No turning vanes are used to direct the water. The problem with such a tank is that large amounts of turbulence are developed, and loss of water velocity results. Therefore, more power is needed to circulate the water, and swimming comfort is adversely affected by the turbulence. The preceding prior art is incorporated by reference herein.
U.S. Pat. No. 5,044,021 issued to James Murdock for a “Continuous swimming apparatus” discloses and claims a swim treadmill which is said to avoid the power and size shortcomings of the prior art by providing a compact swimming apparatus. The apparatus consists essentially of a tank adapted to contain water and having a swimming area within the tank. Water flows through the swimming area from a water entrance end to a water exit end and returns to the water entrance end via a return path positioned adjacent the swim area. Water circulation means is included in the return path for propelling the water through the return path and through the swimming area. A plurality of vanes are located in the return path to direct the water from the return path to the entrance end of the swimming area and from the exit end of the swimming area to the return path. The vanes help to minimize power losses by minimizing water turbulence. The vanes are spaced in such a way as to create a horizontal velocity gradient across the swimming area whereby water closer to the center of the swimming area has a higher velocity than water near the sides of the swimming area. The preceding prior art is incorporated by reference herein.
UK Patent GB 2,296,861, issued to Spaform Limited, Jul. 8, 1998, teaches arranging circulating passages to communicate with the delivery passages externally of the tank portion, and by mounting the (single) propeller means in the delivery passage, the propeller means can be mounted externally of the tank portion to facilitate servicing. Water is circulated in the tank portion so that a swimmer can swim against the first flow generated by water being propelled into the tank portion through the delivery passage by the (single) propeller means. Water is circulated back in the tank portion on either side of the main first flow and in counterflow thereto. Thus space is not wasted by arranging ducting externally of the tank portion for returning water from one end or side of the tank portion. The water in the tank portion is preferably intended to be circulated at or just below the water surface in a generally horizontal plane. As shown, the bottom of the exercise pool has a sloped bottom to further facilitate return of the circulating water flow. The preceding prior art is incorporated by reference herein.
U.S. Pat. Nos. 9,038,208 and 9,428,928 as well as published US Pat. Appl. No. 20160237708 (hereinafter “Ferriss et al.”) also teach and disclose a single propeller or propeller means within a swimming pool to produce a circulating water flow, in which a single plenum arrangement is used to create circuitous water flow paths within the swimming compartment of the swimming pool. As disclosed the method of operating a swimming pool with a circulating water flow includes the steps of discharging a jet of water and splitting the flow of water. The discharging step including the discharging of a jet of water from an outlet at a head end of the swimming pool into a swimming compartment, whereby the jet of water flows in a primary flow path toward a foot end of the swimming compartment. The splitting step including the splitting of the flow of water to define two circuitous flow paths, each said flow path having a return flow path flowing within said swimming compartment in a direction generally opposite to said primary flow path back toward said head end. The foot end of Ferriss as shown in FIG. 1 is seating for a spa or hot tub, inherently providing curved surfaces which appear to assist with current flow diversion and re-direction back to the head end. The preceding prior art is incorporated by reference herein.
Published US Patent application 20170204628 entitled “Swim Spa” listing Livingston, Jr. as an inventor teaches a forward current created by pumping equipment which directs the forward current from the head end of the tank, past a swimmer in the water to a foot end of the tank, allowing the swimmer to swim in place. A diverter having a curved surface is positioned at the foot end of the tank for redirecting the forward current toward the sidewalls and then back to the head end for recirculation. As taught by Livingston, the diverter may only apply curved surfaces for turning the forward current. Additional prior art of interest include U.S. Pat. No. 1,731,554 issued to M. I. Wheeler for “Swimming Pool” and U.S. Pat. No. 722,232 issued to Hoeglauer for “Bathtub”. The preceding prior art is incorporated by reference herein.